Hydraulic molding machines



April 9, 1963 D. A. HuELsKAMP HYDRAULIC MoLDING MACHINES 2 Sheets-Sheet1 Filed March l0, 1958 -..-J n@ c April 9, 1963 D. A. HUELSKAMP3,084,512

HYDRAULIC MOLDING MACHINES Filed March l0, 1958 2 Sheets-Sheet 2INVENTOR. t a/vfup. #yam/4M? United States Patent 3,084,512 HYDRAULICMLDNG MACHNES Denain A. Hneiskamp, Mount Giiead, Ohio, assigner toKoeln-ing Company, Miiwaniree, Wis., a corporation of Wisconsin FiledMar. 1t), 195, Ser. No. '720,228 12 Ciaims. (Cl. 6th-52) This inventionrelates generally to hydraulically actuated molding machines of the typehaving a mold clamp assembly for quickly closing, clamping and opening amold. v

In injection molding machines and the like, it is common to effect aninitial high-speed movement of the main ram to mold closing position bymeans of a smaller booster ram. The advantage of this is that a givenamount of pressure iiuid supplied to the booster cylinder will effect amuch faster and greater ram movement than it would if supplied to themain ram cylinder. This construction however requires that Huid prellmeans be provided for keeping the main ram cylinder filled with fluid asthe main ram is moved under the action of the booster ram. It alsorequires that valve means be provided for shifting the flow of pressureliuid from the booster ram to the main ram when the latter reaches thatpoint in its travel at which full ram pressure is desired. Thisconstruction further requires that valve means be provided for quicklyclosing the large preill line to the main cylinder just before theshiftover of the high pressure uid which is commonly at a pressure of3000 lbs/sq. in. or higher.

The prior art machines providing the above-mentioned apparatus havepresented severe manufacturing and assem* bly problems particularly inthe construction of the main cylinder casting. They have furtherrequired the use of at least two large and expensive valves which arevery difficult to synchronize for obtaining optimum clamping speed.

Accordingly, an object of the present invention is the elimination ofcertain objectionable features of existing mold clamping assemblies foreffecting improvements in their operation and economies in theirmanufacture and assembly.

Another object of the present invention is to provide a mold clampassembly of the booster ram type in which the booster ram, prefill valveand the clamp main cylinder shiftover valve are combined into one simplesub-assembly which inherently provides proper valve sequencing.

A further object of the present invention is to provide a booster ramtype mold clamp assembly which does not require large high-pressurepipes and fittings. A more detailed object is to provide a constructionin which the booster ram assembly may be easily removed and insertedwithout necessity for removing the main ram.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds, taken in connection withthe drawings in which:

FIGURE l is a side elevation partially in section of a mold clampassembly embodying the present invention;

FIG. 2 is a fragmentary cross-sectional view of the same assemblyshowing the condition of the booster ram assembly as the main ram ismoved by the booster ram.

FIG. 3 is a fragmentary cross-sectional view of the apparatus of FIG. 2showing the condition of the booster ram assembly when high pressurefluid is supplied t the main ram.

FIG. 4 is a diagrammatic representation of a suitable hydraulic systemfor utilizing apparatus embodying the present invention; and

FIG. 5 is a cross-sectional view of a booster ram assembly embodying analternative embodiment of the present invention.

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While the invention is susceptible of various modifications, certainpreferred embodiments have been shown in the drawings and will bedescribed below in considerable detail. It should be understood thatthere is no intention to limit the invention to the specific formsdisclosed, but, on the contrary, the intention is to cover allmodifications and alternative constructions falling within the spiritand scope of the invention as expressed in the appended claims.

In FIG. l of the drawing, there is shown an injection molding machineembodying the present invention and having a frame 11 with an injectionmechanism assembly 12 and a mold actuating or clamp mechanism assembly13 on adjacent portions of the frame. The injection mechanism assembly12 is of conventional form and includes an injection nozzle 14 throughwhich plastic material passes in a well-known manner into a cavitydefined by mold halves 15, 16.

In order to hold the mold halves in face-to-face contact during theinjection of the plastic material and to permit subsequent removal ofthe molded piece, a horizontally movable platen 18 carries one mold half16 toward and from a stationary die head 17 which supports the secondmold half 15. For this purpose the mold clamp assembly 13 is providedwith a main ram 19 which is horizontally reciprocable in a ram cylinder21 and which has secured to its outer end the movable platen 18.

In practicing the present invention, means are provided for operatingthe main ram 19 to give rapid closing movement of main ram 19 with aslow but powerful final approach and clamping action. For this purpose,the clamp assembly comprises the main ram assembly and a novel boosterram assembly having a sequentially-acting valve assembly.

The ram cylinder 21 is formed in a generally cylindrical housing 20 by alongitudinally positioned, open-ended cylindrical bore. To actuate theram 19, pressure fluid may be applied to a pressure chamber behind theram for forward movement or to an annular cavity 22 surrounding the ramfor return movement. For the latter purpose, the forward or outer end ofthe cavity 22 has suitable seals, such as ring seals 24, to preventescape of pressure fluid, and to permit reciprocation of the main ram19'. The rear or inner end of the ram 19 has an enlarged portion 25forming an annular area against which the pressure uid acts to returnthe ram. The enlarged portion or ange has suitable fluid seals, such aspiston rings 26, which likewise permit reciprocation of main ram 19.Return movement of the ram 19 is limited by an internal abutment orshoulder 2S formed in the inner wall `of the main ram cylinder bore 21.Forward movement is limited by engagement of the mold halves 15, 16.

To provide a rapid closing movement of the main ram 19, and a slow,powerful final approach and clamping action, means are provided forapplying pressure fluid to differential areas on the rear or inner endof the main ram 19. For rapid traverse, the means are in the form of abooster ram assembly 29 to apply uid pressure to a relatively small areaofthe main ram 19. In the present instance, the booster ram assemblyincludes a stationary booster ram 30 of cylindrical shape which projectsforwardly into an axial `bore or compartment 31 called the booster ramcylinder, formed centrally in the rear or inner end portion of the mainram 19.

The booster ram cylinder 31 is of suiiicient length to allow axialclearance between the forward end of the booster ram 30 .and the bottomof the compartment when forwardly in rapid forward or closing movement.

Referring also to FIGS. 2 and 3 of the drawings, sealing the open rearend of the booster compartment or cylinder 31 and maintaining thebooster and main rams in substantially coaxial sliding relation, is `atubular collar 32 seated in a countcrbore 34 in the rear end portion ofthe booster cylinder 31. The tubular collar 32 has an inner diameterwhich permits sliding engagement with the booster ram 3% and is held inposition by an annular plate or retaining ring 35. This retaining plateis secured to the rear face of the main ram 19, and has its inner edgepor-tion extending radially inwardly over the exposed end of the collar32 blocking rearward displacement of the latter. For the purpose ofproviding clearance, the retaining plate 35 is preferably recessed intothe end face of the main ram 19 by mounting it on the bottom surface ofa second counterbore 36 having a diameter large enough to receive theretaining plate 35.

The booster ram Sti is supported at its outer end by a hollow,cylindrical housing 39 which is secured as by bolts 4d to a rear endsection 41 of the main ram cylinder housing 20, which is of reduceddiameter Ito mate with the forward end of the booster ram housing 39 andform a fluid-tight joint between the housings. However, it should benoted that the opening in the end section 41 is of sufficient 4diameterto permit passage therethrough of the booster ram assembly. The boosterram 3i] extends through the rear end wall 42 of its housing 39 and issecurely mounted on the rear Wall by a nut 44 received on a threadedsection 45 of the booster ram. Tightening of the mit 44 against theoutside of the wall 42 draws an external flange or shoulder 46 on theram 30 into engagement with the inside of the wall 42 to hold the ramsecurely in position.

A second `dierential pressure area on the main ram is provided by theremaining annular area on the rear end face 3d surrounding the boosterram cylinder 31, and includes the annular retaining plate 35 and anyexposed portion 39 of its receiving counterbore 36. The fluid applied tothe second diderential pressure area of the main ram is received in lachamber 47 formed by the rear section 41 of the main ram cylinderhousing 20 and the forward end of the booster ram housing 39. Thechamber, of course, includes the main ram cylinder 21 as the ram 19moves outwardly.

For conducting pressure fluid to the operative ram areas and foractuating control mechanisms to be described later, the booster ram 30is further provided with conduit means extending axially thereof fromthe rear to the forward end of the booster ram. The conduit meanscomprises a longitudinal bore 48 extending from a suitable high pressureinlet tting 49 at its rear end forwardly `to its forward end at whichplace the bore is in communication with the booster ram cylinder 31.Thus, when fluid is supp-lied to the inlet fitting 49, the pressure isapplied continuously to the first or booster pressure area of the mainram 19.

Because of the relatively small cross-sectional yarea of the booster ram30 and booster ram cylinder 31, only a small volume of pressure fluidneed be supplied to move the main ram 19 forwardly. Consequently, for agiven rate of supply of pressure fluid, the main ram 19 is pushedforward rapidly to provide rapid traverse for closing the mold. It lwillbe appreciated, however, the force moving the ram is relatively smallbecause of the small pressure area at the bottom of the booster ramcylinder 31.

Further, means are provided for minimizing the amount of pressure fluidwhich must be delivered to the clamping assembly for ,applying clampingpressure. In more detail, means are provided for controllably preillingthe main ram pressure chamber 47 with fluid under little or no pressureduring rapid traverse of lthe main ram 19 to permit at the cessation ofrapid traverse rapidly increasing the pressure in the main ram chamberto clamp the molds together. In the illustrated embodiment of FIG. 1, atank 52, called a preiill tank, is mounted above the clamping assemblyand contains hydraulic uid of the same kind as that to be used in thehigh-pressure conduits. A Short pipe 54 leads from the bottom of theprell tank to a suitable opening 53 in the top of the booster ramhousing 39. The preiill fluid flows by gravity from the preiill tankthrough the pipe 54 into an annular space or passage 55 `formed betweenthe booster ram 3b and the inside of the booster ram housing 39. Theforward end of the annular passage 55 is open for communication with therear face of the main ram 19. Consequently, as the main ram movesforwardly under the action of the .booster ram, preiill liuid iiows intothe expanding space behind the main ram keeping that space full offluid. Thereafter pressure fluid may be supplied to the main ram throughthe ports 51 which provide a fluid passage- Way between Ithe booster rambore 48 and the outside surface of the ram located in the liuid chamber47.

For controlling the iiow of preiill liuid as well as applying highpressure to it for clamping, a simple and compact valve means isprovided. ln the illustrative ernbodiments of the invention shown inFIGS. 1 4, the valve member is formed by a tubular or cylindrical sleeve56 slidably mounted on the intermediate portion of the booster ram 39'and having integral first and second concentric portions 58, S9. Theforward portion 53 overlies booster ram section 60 in which are locatedthe radial pressure iiuid ports 51, and the rear portion 59 overlies theadjacent rearwardly positioned section 61 of the booster ram Sill. Theinternal diameters or" the valve portions 60, 61 and external diametersof the respective booster ram sections are substantially equal toprovide a sliding fit between the sleeve 56 and ram Sti.

The forward portion 58 of the sleeve and the underlying booster ramsection 60 have greater diameters than the rear portion and section 59,66, to form a rearwardly facing abutment or shoulder 62 on the ram 35B,and a forwardly facing shoulder 63 on the sleeve which limits itsforward movement and which provides a surface for receiving fluidpressure in a manner to be hereafter described. Rearward movement of thevalve sleeve 56 is limited by engagement between an annular bevelledvalve seat 64 on the outer rear corner of the sleeve, and a mating,annular, bevelled seat 65 on the inside forward end of the booster ramhousing 39.

By the described forward and rearward sliding movement, the valve sleeve56 controls both the admission of prefill fluid and the application ofpressure to the main or second pressure area of the main ram 19. In itsforward limit position, sleeve 55 covers and therefore closes the radialports 51 in the booster ram, preventing loss of pressure uid to the mainpressure area of the main ram 19. At the same time, the annular valveseat 64 on the rear of the sleeve 56 is spaced from the mating valveseat 65 on the booster ram housing opening passage 55 and permits prellfluid to iiow into or out of the main ram pressure chamber 47. In itsrearward limit position, the bevelled valve seats 64, 65 are engaged sothat the valve sleeve 56 blocks the open forward end, or port, of theannular preiill liquid passage 55 and prevents flow of preiill fluid,while uncovering the ports 51 to permit high-pressure iuid from inlet 49to enter the main ram pressure chamber 47. The obvious advantage of thisconstruction is that the opening of the one fluid passageway effects theclosing of the other, and vice Versa. in this manner there is providedan inherently correct sequencing of the two valving functions.

Actuation of the valve means positioned within the booster ram assemblyis accomplished by applying biasing forces to the valve sleeve. In theembodiment of FlGS. 1 3, a forward biasing force is applied to the valvesleeve 56 by a compression coil spring 34 which is positioned around thebooster ram Sil between the rear wail 42 of the ram housing and the rearface of the valve sleeve 56. This force moves the sleeve Se to itsforward or initial position which opens pretill passage 5S and closesthe high-pressure ports 51.

' To move the sleeve 56 to its rearward position, an auxiliary or pilotpressure fluid is utilized. For this purpose, the booster ram 30 has asecond duid conduit or bore `dit which extends longitudinally of the ramSil and substantially parallel to the high-pressure conduit or bore 43.Communicating with tne rear end of the second conduit or bore, is aninlet fitting titi for receiving pilot or control pressure fluid. At itsforward or inner end, conduit S5 communicates with the exterior surfaceof booster ram 3G through port S7 located at the juncture of thesections 6d, 6i underlying the valve sleeve 56. At the intersection ofport 87 with exterior surface, a circumferential groove Si is formed inthe exterior of the booster ram intermediate the sections ed, 6i, toconduct control iiuid from port `57 to the forwardly facing internalshoulder 63 on the valve sleeve. The shoulder d3 may have a slight bevelor taper to permit control fluid to press against the latter even whenit is in the forward position against shoulder 62. Sealing means, suchas rings 99, may also be used to limit leakage of iiuid between the ram3d and sleeve 56.

In the embodiment of the invention illustrated in FIG. 5, the valvemeans and booster ram assembly are shown in a somewhat modified form.The booster ram in this embodiment comprises a hollow, cylindricalmember 7d of substantial uniform diameter which is welded or otherwisesuitably secured by a fluid-tight connection to the rear end wall 71 ofa cylinder booster ram housing 72 similar to the housing 39 of FIGS.1-3. The rear wall 71, for convenience of manufacture and assembly, isshown as a circular plate fastened by bolts 73 on the rear of thehousing 72. Centrally of the rear wall Plate 7l is an opening forintroduction of high-pressure fluid to the center or bore 74 of thehollow booster ram 7i). Thus, the embodiment of FlG. 5 also has branchcircuits for the high-pressure fluid. One branch extends axially to theforward end of the booster ram in the same manner described previously,and a second branch is provided -by radial ports 75 which communicatewith the main ram pressure chamber in the same manner as ports S1 ofFIGS. l-3.

The ram housing 72 of FIG. 5 also has a preiill port 76 in its topportion and an annular cavity 77 surrounding the forward portion of thebooster ram 75 for the same purposes as the port 53 and annular cavityS5 of FIGS. l3.

The valve means of FIG. 5 comprises an elongated cylindrical sleeve 78surrounding the booster ram 76 and axially slidable thereon. Sleeve 78extends rearwardly of the prelill port 76 and has sealing rings 79 onits rear portion to close the rear of the preiill cavity 77. The forwardend of the valve sleeve 78 is enlarged to provide a rearwardly facingannular bevelled valve seat 3d which mates with an annular bevelledvalve seat til formed on the inner forward edge of the ram housing 72when the sleeve 7d is in its rear position in the same manner as themating valve seats 64, e5 of FIGS. l-3. ln the forward position ofsleeve 78, the radial high-pressure ports 75 are closed as shown indotted outline in FIG. 5. Consequently, although of modified form, thevalve means of FIG. 5 provides the same valving action as the valvemeans of FIGS. 1 3.

Still referring to FIG. 5, means are provided for actuating the valvesleeve 78 by pilot or control uid in both its forward and rearwardmovement. For this purpose, the booster ram housing 72 and valve sleeve78 are constructed to provide a double-acting piston arrangement. Therear portion of the booster ram housing 72 has an increased diameter toform a valve actuation cylinder 98 interposed between the rear wallplate 71 and an internal shoulder 99. The piston section 100 on the rearend of the sleeve 78 provides in `cooperation with the cylinder 98 adouble-acting ram for effecting reverse movements of said sleeve.Leading to opposite ends of the valve actuating cylinder 93 are pressurefluid ports `101, 102 and conduits 103, 104. Thus, by alternativelyconnecting the fluid ports to the output of a pilot or control fluidsystem, such as illustrated in FIG. 4, and to drain, the valve sleeve 73may be readily actuated between its forward limit position, determinedby engagement of piston 100 and shoulder 99, and its rearward limitposition determined by engagement of the pretill valve seats 8d, Sil.

Operation of the structure illustrated in FIGS. 1-3 will now bedescribed with reference to FIG. 4 of the drawings which showsdiagrammatically fluid supply systems operatively connected to theclamping assembly. The main ram 19 and valve means are shown in theirinitial positions with the ram i9 in its return or retracted position.High pressure fluid is supplied to the clamping assembly by pump 91,through a solenoid-operated reversing valve 92. When the Forwardsolenoid of valve 92 is energized, the left-hand section of the valveadmits high-pressure fluid to the high-pressure inlet fitting throughhigh-pressure conduit 48 and into the booster ram cylinder 3l, causingrapid advance of the main ram 19. Advance of the main ram 19 creates asuction behind it which draws preiill fluid into the main cylinderhousing Ztl Vas previously described.

When the rapid closing mold clamp mechanism has proceeded sufficientlyto attain the desired platen position relative to diehead 117, pilot orcontrol pressure fluid is supplied by pilot pump 93 throughsolenoid-operated cylinder shift valve 94 to inlet 85. The pilot fluidthen flows through the second conduit in booster ram 30 and out of portS7 into the annular groove 8S where it bears upon a bevelled innershoulder of the valve 56. The force of the pilot fluid upon shoulder 63is such that it exceeds the fixed forward thrust of compression spring8d and urges sleeve 56 toward its rearward position. As sleeve 56reaches its rear position, the valve seats 64, 65 close the prefillpassage 55 to prevent reverse flow of Huid therethrough and permitbuild-up of pressure in the cylinder 47.

As the valve sleeve S6 moves rearwardly, the forward end of the sleeve,which may be bevelled as at 39, reaches and passes the ports 5f,permitting flow of high-pressure lluid through the ports 51 into themain ram pressure-fluid chamber 47 in clamp cylinder 20. The fluid fromthe high-pressure circuit now acts upon the main or second area of themain ram in addition to acting on the first or booster area. The totalram area acted upon by the high-pressure fluid is thus greatlyincreased, giving a slower final closing of the mold halves with anincreased clamping force.

To maintain clamping force on the molds, the reversing valve 92 may beleft in the forward position, or if desired, may be shifted to theneutral position, as shown in FIG. 4. Control circuits for effectingoperation of valves 92 and `@f4 in the manner and sequence hereindescribed are well known to those skilled in the injection moldingmachine art. For example, in U.S. Patent No. 2,680,883, issued June 15,1954, there is illustrated a control circuit in which limit switches areused for effecting operation of a main pressure valve and a highpressure distributing valve at selected positions in the travel of themain ram of an injection molding machine.

To retract the main ram 19, the Reverse solenoid of valve 92 isenergized to bring the right-hand section of the valve into the circuit.This opens the high-pressure inlet e9 to drain and directs the output ofthe high-pressure pump 91 to the return chamber 22 of the main ramcylinder 2l. Substantially simultaneously with the withdrawal ofhigh-pressure fluid from the inlet and booster ram conduit 4d, the pilotcircuit is also opened to drain by shifting the pilot valve 94 so thatthe pressure in the pilot circuit is reduced sufficiently to allowspring 84 to open prell passage 55' and close booster ports 5l. Whilethe thrust of spring 84 is thus relieved of resistance from the pressurein the pilot circuit, it still encounters res,os4,512

sistance from the pressure uid in the main ram pressure chamber. rhispressure however is lost through ports l, and conduit `rib, to drain.When the pressure is reduced sufficiently for spring Sd to effect apartial opening of the prelill passage 5S, the pressure remaining incylinder 47 is lost and the sleeve means 56 completes its forwardmovement to completely open prell passage 5S and close booster ports 5l.The remaining fluid in cylinder d'7 is then returned to the prefill tank52 in response to the rearward movement of main ram lil@ resulting fromthe introduction of pressure fluid in pushback cavity 22 as previouslydescribed.

The sequence of operation of the structure of FIG. 5 is the same as thatof FIG. 4 except that forward movement of the valve sleeve 78 is causedby forward biasing hydraulic` pressure rather than the elastic orresilient force of spring 84.

lt will be understood that other high pressure and control or pilotpressure supply circuits and systems may be used depending on theparticular application of the invention.

I claim as my invention:

l. In an apparatus of the type described, the combination comprising, aclamp cylinder; a main ram; a booster ram having a generally cylindricalshape; a boos-ter ram housing coacting with said booster ram to deiinetherebetween a preilll passage for supply of prell fluid :to saidcylinder; said booster ram having a plurality of independent conduitmeans defined therein axially thereof, one of said conduit meansincluding one branch for conducting pressure lluid to said booster ram,and a second branch including radially extending booster por-t meansdefined in a medial portion of said ram; and a sleeve valvecircumscribing said booster ram in sliding engagement therewith adjacentsaid booster port and selectively actuable axially along said boosterram into and out of blocking engagement with said booster port meansWhile simultaneously opening and closing said preiill port, another ofsaid conduits in said booster ram being connected for applying pilotpressure to said sleeve means for selectively actuating said sleevemeans independently of the fluid pressure in said first-mentionedconduit means.

Z. A combination preiill valve and main clamp shiftover valve assemblyfor use With a molding machine having a booster ram for eiecting aninitially fast closing movement of a mold and a main ram for effecting afinal slow closing movement of the mold, said valve assembly comprising,a valve housing dening a passageway for preiill fluid between a prefillfluid tank and said main ram; high pressure fluid conduit meanspositioned within said housing for supply of pressure fluid to Saidbooster ram and having port means for supply of pressure fluid to saidmain ram; a valve member positioned within said housing, said valvemember being movable to one position where it opens said preilll fluidpassageway and blocks said high pressure ilu-id port means and beingmovable to another position in which it blocks the said prell fluidpassageway to the ltank and `opens said high pressure fluid port meansfor supply of high pressure fluid to said main ram; and meansindependent of the pressure in said fluid conduit means for effectingmovement of said valve member to said another position prior to closingor" said mold whereby a final slow closing movement of said mold may beeffected.

3. A prelll valve assembly for use with a horizontally disposed clampingcylinder in an injection molding machine, said assembly comprising, ahousing having a centrally disposed cavity and flange means encirclingthe mouth of said cavity for eecting mounting of said housing at therear end of a clamping cylinder; a booster ram including a high pressurefluid conduit centrally disposed within said cavity and defining withsaid housing an annular prelill fluid passageway; means defined in thetop of said housing for connecting said passageway with a prell fluidconduit; fluid port means defined in said high pressure uid conduit forsupply of high pressure iluid to the clamping cylinder; a valve membermovable within said cavity to a first position for closing said highpressure fluid port means and opening said pretill fluid passageway,said valve member being movable to a second position for 4opening saidhigh pressure fluid port means and closing said preiill fluidpassageway; and means including Ia hydraulic ram connected to saidmovable valve member for effecting actuation thereof at any selectedposition of said main ram; said actuating means also inoluding conduitmeans connected for supply of pilot pressure fluid to said valveactuating hydraulic ram and valve means for selectively controlling thesupply of pilot pressure iluid to said valve actuating hydraulic ram.

4. An injection molding machine clamp mechanism comprising, a main ramfor eiecting slow mold clamping movement; a booster ram for effectinghigh speed mold clamping movement of said main ram; prell fluid conduitmeans for supplying prefill fluid to said m-ain ram; high pressure fluidconduit means positioned concentrically with said preiill fluid conduitmeans and having one branch for supply of high pressure fluid to saidbooster ram and a second branch for supply of high pressure lluid tosaid main ram; a `sleeve valve member movably mounted on said highpressure fluid conduit for movement to one position to lopen said prellfluid conduit and close said second branch off rsaid high pressure fluidconduit for effecting high lspeed low pressure movement of said mainram, said valve member being movable to a second position prior to moldclosing for closing said prelfill fluid conduit and opening said secondbranch of said high pressure fluid conduit for eecting low speed highpressure movement of said main ram; and means for moving said valvemember to either `of said positions at any selected position of saidmain ram.

5. In an injection molding machine, an improved assembly for selectivelyeffecting high and low speed movement of a platen, said assemblycomprising a main ram for eiecting low speed platen movement; a boosterram connected to a booster ram chamber in said main ram for effectinghigh speed platen movement; a main ram housing defining a chamber forsaid main ram and having at the rear end thereof an opening forinsertion therethrough of said booster ram and for passage of preiillfluid; a booster ram housing removably secured to said main ram housingfor supporting the rear end of said booster ram, said booster ramhousing ydefining a passageway for flow of preiill fluid into and out ofsaid main ram chamber; conduit means defined in said booster ram havinga first port for conducting high pressure fluid to the booster ramchamber and a second port for conducting high pressure fluid to the mainram chamber; valve means mounted on said booster ram conduit means formovement in one direction to open said prell fluid passageway and blockflow of high pressure fluid through said second high pressure port foreecting high speed platen movement, and for movement in anotherdirection to block said prefll fluid passageway and open said secondhigh pressure port for effecting slow speed platen movement; and meanscontrollable independently of the fluid pressure in said conduit meansfor effecting movement of said valve means at any selected position ofsaid main ram.

6. in a molding machine, a cylinder, a main ram reciprocable thereinwith the volume in said cylinder behind said main ram constituting amain ram cavity, a booster ram stationary relative to said cylinder andprovided with ports, said main ram having a booster ram cavity thereinand said booster ram entering said last cavity, a combined preiill and`change-over valve comprising a sleeve surrounding said booster ram andhaving an enlarged closure element in said main ram cavity, a seat inthe inner end of said cylinder for said closure element, said valvehaving an actuating piston also surrounding said booster ram, saidcylinder having a reduced bore beyond said inner end thereof serving asa cylinder for said actuating piston, means for seating said closureelement on said seat, said valve when in unseated position byintroduction of uid under pressure to said reduced bore, establishingcommunication between a luid reservoir and said main ram cavity throughsaid seat and past said enlarged closure element, and at the same timecutting off communication between said cavities by said sleeve coveringsaid ports, and when in seated position blocking communication betweensaid fluid reservoir and said main ram cavity and at the same timeestablishing lcom-munication between both of said cavities by saidsleeve uncovering said ports whereby fluid under pressure supplied tosaid booster ram cavity also ows to said main ram cavity for slowadvance of said main ram.

7. In a molding machine, a cylinder, a main ram reciprocable thereinwith the volume in said cylinder behind said main ram constituting amain ram cavity, a booster arm stationary relative to said cylinder,said main ram having a booster ram cavity therein and said booster ramentering said cavity, a combined prell and change-over valve surroundingsaid booster ram and having a closure element, a seat in said cylinderfor said 4closure element, said valve having an actuating piston, saidvalve when in one position establishing communication between a fluidreservoir and said main ram cavity and cutting off communication betweensaid cavities, and when in another position cutting off communicationbetween said uid reservoir and said main ram cavity and establishingcommunication between both of said cavities whereby fluid under pressuresupplied to said booster ram cavity also Hows to said main ram cavityfor slow advance of said main ram, said cylinder having a pull backcavity, a main pump, a first valve for forward and return control of theoutput of said main pump to and from said booster ram cavity and saidIpull back cavity, a pilot pump, a second valve for on-off control ofthe output from said pilot pump to said actuating piston of sai-dcombined prelill and change-over valve, and an electric circuit foractuating said first and second valves to effect forward and returnmovement of said main ram and to effect during the forward stroke ofsaid main ram and before the end thereof movement of said combinedpreiill and changeover valve from prell position to change-overposition.

y8. In a molding machine, a cylinder, a main ram reciprocable thereinwith the volume in said cylinder behind said main ram constituting amain ram cavity, a booster ram stationary relative to said cylinder,said main ram having a booster ram cavity therein and said booster ramentering said cavity, a combined preiill and change-over valvesurrounding said booster rarn and having a closure element, a seat insaid cylinder for said closure element, said valve having an actuatingpiston, said valve when in one position establishing communicationbetween a fluid reservoir and said main ram cavity and cutting offcommunication between said cavities, and when in another positioncutting off communication between said fluid reservoir and said main ramcavity and establishing com,- munication between both of said cavitieswhereby uid under pressure supplied to said booster ram cavity alsoflows to said main ram cavity for slow advance of said main ram, saidcylinder having a pull back cavity, a main pump, a iirst valve forforward and return control of the output of said main pump to and `fromsaid booster ram cavity and said pull back cavity, a pilot pump, asecond valve for on-off control of the output from said pilot pump tosaid actuating piston, and an electric circuit for actuating said firstand second valves to effect forward and return movement of said main ramand to effect during the forward stroke of said main ram and before theend thereof movement of said combined prelill and change-over valve fromprell position to change-over position.

9. In a molding machine, a cylinder, a main ram' reciprocable thereinwith the volume in said cylinder behind said main ram constituting amain r-am cavity, a booster ram, `a combined preill and change-overvalve having a closure element, a seat in said cylinder for said closureelement, means normally seating said closure element on said seat, saidvalve when in unseated position establishing communication between a uidreservoir and said main ram' cavity, and when in seated positionblocking communication between said liuid reservoir and said main ramcavity and establishing communication between said booster ram and saidmain ram cavity whereby uid under pressure supplied to said booster ramalso flows to said main ram cavity for slow `advance of said main ram,said cylinder having a pull back area, a main pump, a rst valve forforward and return control of the output of said main pump to and fromsaid booster ram and said pull back area, a pilot pump, a second valvefor on-otf control of the output from said pilot pump to said actuatingpiston of said combined prell and change-over valve, `an electriccircuit for actuating said rst and second valves to iirst supply oilfrom said main pump to said booster ram and from said pilot pump to saidcombined prell and change-over valve for moving it to said anotherposition, lthen supply oil to said main ram and said booster ramtogether while permitting said combined prell and change-over valve to`assume said seated position, and then supply oil to said pull back'area to thereby return said main ram to its initial position while saidprefill valve is again in said another position.

l0. In a molding machine, a main ram, a booster ram, a combined prefilland change-over valve having an actuating piston, said valve when in oneposition establishing communication between a iiuid reservoir and saidmain ram and when in another position establishing communication betweensaid rams, a main pump, a irst valve for forward and return control ofthe output of said main pump to and from said rams, a pilot pump, asecond valve for on-off control of the output from said pilot pump tosaid `actuating piston, and an electric circuit for actuating said firstand second valves to effect forward and return movement of said main ram`and to effect during the forward stroke of said main ram and before theend thereof movement of said combined prell and changeover valve fromsaid one position to said another position and during the return strokeof said main ram' to said one position.

ll. In a molding machine, a main ram, a booster ram, a combined prelland change-over valve, actuating means therefor, said valve when in oneposition establishing communication between a fluid reservoir and saidmain ram and cutting off communication between said rams, and when inanother establishing communication between said rams for slow advance ofsaid main ram, `a main pump, a pilot pump, a first valve for forward andreturn control of the output of said main pump to and from said rams, Iasecond valve for oil-off control of the output from said pilot pump tosaid actuating means, `control means operable in different positions ofsaid main ram for operating said first and second valves, said main rambefore the end of its forward stroke effecting through said controlmeans movement of said second valve to off position and thereby saidcombined preiill and change-over valve from said one position to saidanother position, said main rain at lthe end of its forward strokeeffecting through said control means shift of said first valve fromforward to return positions and said second valve to on position andthereby said combined prefill and change-over valve from said anotherposition to said one position for the return stroke of said main ram,and said main ram at the end Iof its return stroke effecting throughsaid control means return movement of said first valve lto neutralposition to thereby stop said main ram at the end of an operating cyclethereof.

12. In a molding machine, a cylinder, a main ram reciprocable thereinwith the volume in said cylinder behind said main ram constituting amain ram cavity, a

booster ram, a combined prell `and change-over valve having a closureelement, ya seat in said cylinder for said closure element, means forseating said closure element on said seat, said valve when in unseatedposition establishing communication between 4a fluid reservoir and saidmain rain cavity, and when in seated position blocking communicationbetween said uid reservoir `and said main ram cavity `and establishingcommunication between said booster ram and said main ram cavity wherebyuid under pressure supplied to said booster ram also flows to said mainram cavity for slow advance of said main rarn, said cylinder having Iapull back area, a main pump, a first valve lfor forward and returncontrol of the output of said main pump to and from said booster ram andsaid pull hack area, a pilot pump, a second valve for on-of control ofthe output from said pilot pump to said actuating piston of saidcombined prell and change-over valve, `an

L? electric circuit for actuating said first and second valves to firstsupply oil from said main pump to said booster ram `and from said pilotpump to said combined prell and changeover valve for moving it to saidanother position, then supply oil to said main ram and said booster ramtogether while permitting said combined prell and change-over valve toassume said seated position, and then supply oil to said pull back areato thereby return said main ram to its initial position while said prellvalve is again in said another position.

References Cited in the le of this patent UNITED STATES PATENTS1,926,692 Tarbox Sept. 12, 1933 2,110,972 Dinzl Mar. 15, 1938 2,152,837Cannon Apr. 4, 1939 2,878,648 Norman et al. Mar. 24, 1959

1. IN AN APPARATUS OF THE TYPE DESCRIBED, THE COMBINATION COMPRISING, ACLAMP CYLINDER; A MAIN RAM; A BOOSTER RAM HAVING A GENERALLY CYLINDRICALSHAPE; A BOOSTER RAM HOUSING COACTING WITH SAID BOOSTER RAM TO DEFINETHEREBETWEEN A PREFILL PASSAGE FOR SUPPLY OF PREFILL FLUID TO SAIDCYLINDER; SAID BOOSTER RAM HAVING A PLURALITY OF INDEPENDENT CONDUITMEANS DEFINED THEREIN AXIALLY THEREOF, ONE OF SAID CONDUIT MEANSINCLUDING ONE BRANCH FOR CONDUCTING PRESSURE FLUID TO SAID BOOSTER RAM,AND A SECOND BRANCH INCLUDING RADIALLY EXTENDING BOOSTER PORT MEANSDEFINED IN A MEDICAL PORTION OF SAID RAM; AND A SLEEVE VALVECIRCUMSCRIBING SAID BOOSTER RAM IN SLIDING ENGAGEMENT THEREWITH ADJACENTSAID BOOSTER PORT AND SELECTIVELY ACTUABLE AXIALLY ALONG SAID BOOSTERRAM INTO AND OUT OF BLOCKING ENGAGEMENT WITH SAID BOOSTER PORT MEANSWHILE SIMULTANEOUSLY OPENING AND CLOSING SAID PREFILL PORT, ANOTHER OFSAID CONDUITS IN SAID BOOSTER RAM BEING CONNECTED FOR APPLYING PILOTPRESSURE TO SAID SLEEVE MEANS FOR SELECTIVELY ACTUATING SAID SLEEVEMEANS INDEPENDENTLY OF THE FLUID PRESSURE IN SAID FIRST-MENTIONEDCONDUIT MEANS.